It is July 20, 1969. Mission Control at NASA's Houston headquarters joins the watching world in a collective sigh of relief. American astronauts Neil Armstrong and Buzz Aldrin have landed on the moon.

Lunar plaque inscription.(Photo: NASA)

It is only the beginning of mankind's greatest adventure.

At 10:56 p.m. EDT, Armstrong becomes the first human to step into another world, uttering one of modern history's most famous proclamations: "That's one small step for (a) man. One giant leap for mankind."

Aldrin joins him shortly after, remarking on the lunar landscape's "magnificent desolation." The two spend more than two hours collecting samples and taking photographs, as crewmate Michael Collins pilots the command spacecraft, Columbia, in lunar orbit.

Among the items the crew leaves behind is a plaque that reads: "Here men from the planet Earth first set foot upon the moon. July 1969 A.D. We came in peace for all mankind."

Armstrong and Aldrin prepare the lunar module and blast off, returning to Collins and Columbia. They will splash down on July 24, 1969, in the Pacific Ocean. Their mission is complete and their status as national heroes forever sealed.

The team that set out for the Apollo 11 mission in 1969: from left, Neil Armstrong, Michael Collins and Buzz Aldrin. (Photo: NASA via AP)

Armstrong was the first man to walk on the moon. Armstrong commanded the Apollo 11 spacecraft that landed on the moon July 20, 1969. He radioed back to Earth the historic news of "one giant leap for mankind." (Photo: NASA via AP)

Aldrin walks on the moon's Sea of Tranquility, his visor reflecting Armstrong and the lunar module Eagle. The Apollo 11 astronauts carried the National Geographic Society flag with them on their journey to the moon. (Photo: NASA)

Apollo 11 astronauts, from left, Armstrong, Collins and Aldrin were quarantined after their trip to the moon. This photo was used to promote the motion picture "In the Shadow of the Moon." (Photo: NASA via THINKFilm)